This invention relates to a vacuum regulating cartridge used to regulate vacuum pressure of a medical regulating vacuum controller used to control the application of vacuum pressure used to draw bodily fluids from a patient.
In various medical applications vacuum pressure controllers are employed to control the level of vacuum pressure applied to draw bodily fluids from a patient. Such controllers have a housing within which is contained a vacuum pressure meter, an inlet port for connection with a supply of vacuum pressure, a non-regulated or line vacuum chamber in open communication with the inlet port, a regulation vacuum chamber with a valve opening for controlled communication with the line vacuum chamber and an outlet port for connection of regulated vacuum pressure to the patient.
The vacuum regulation chamber includes a well within which is slideably received a vacuum regulating cartridge. The cartridge carries a movably mounted valve head for mating engagement with a valve seat of the valve opening. The carriage body is mounted for sliding movement in response to rotation of a knob to selectively move the valve head to different positions relative to the valve seat. These different positions correspond to different vacuum levels selected from a range of different vacuum pressures.
In known cartridges, the cartridge body contains a bellows-like apparatus which responds to decreases in pressure in the well to move the valve head closer to the valve opening to decrease the effective valve opening and thereby increase the pressure in the well. Likewise, when the vacuum decreases in the well, the bellows respond by moving the valve head away from the valve seat to increase the vacuum. In this way the vacuum which appears at the output port and provided to the patient is regulated relative to the line vacuum.
While the bellows-like apparatus performs its function of automatically moving the valve head for purposes of regulation, it suffers from several disadvantages. Because of the complexity of the bellows-like structure, it is both relatively expensive and difficult to maintain tolerances with respect to the degree of responsive movement for a given change in vacuum pressure. In addition, it has been difficult to reliably obtain the degree of control and regulation over the wider range of control from (0-500 mm Hg vs. 0-200 mm Hg) as is now sometimes required for various applications when using the known bellows-type cartridges.